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By Seren Nurgun, Staff Writer for Save The Water™ | October 21, 2015
Effective and safe water storage increases in value around the world, especially in drought-ridden California. Now more scientists are researching current storage methods. For example, a recent study from the Orange County Water District (OCWD) in Fountain Valley, CA observed unusual spikes “in arsenic after it percolated into soils and sediments from surface basins into underground storage aquifers” (Stanford News, 2015). Unfortunately, the water that absorbed this excess arsenic had already undergone a rigorous purification process, which officials expected to be clean and safe to consume.
Arsenic-contaminated water can cause serious harm to humans and animals. According to the U.S. Environmental Protection Agency (EPA), such water is linked to skin damage, circulatory problems, and increased cancer risks (EPA, 2012). One published study found that “arsenic exposure from drinking water has been associated with heart disease” (Chen et al., 2013). This research followed women and men over 5.9 years and linked their heart function to histories of arsenic exposure. Another study concluded that high-arsenic water can also lead to lung cancer (Dauphiné et al., 2013).
Because of these health risks, Orange County immediately reviewed its water system. The OCWD operates the Groundwater Replenishment System (GWRS), one of the most advanced purification processes in the world. Yet, spiked levels of arsenic were found in monitoring wells, in some cases above the U.S. limit of 10 micrograms per liter. Since incoming water was clean, officials concluded that only the purified recycled water triggered the arsenic spike (Stanford News, 2015).
A team from Stanford University’s School of Earth, Energy & Environmental Sciences found that purified water was deficient in calcium and magnesium. This deficiency caused calcium and magnesium atoms in sediments to migrate into the water, releasing arsenic that was bound to clay particles. In other words, with calcium and magnesium leaving the clay surface, arsenic ions were repelled and entered the water (Stanford News, 2015).
To prevent this in the future, OCWD began adding calcium back into the water during treatment. After consultation with Stanford scientists, they determined this was the most effective long-term solution.
The OCWD and Stanford scientists uncovered a new pathway for arsenic contamination in advanced purification systems. This discovery opens the door for improving global water safety strategies and creating new innovations in treatment to safeguard communities.